This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A173093 #4 Feb 09 2014 10:13:37
%S A173093 1,3,2,3,4,9,32,279,8896,2481705,22077238784,54789193873965015,
%T A173093 1209594115938395614939902976,
%U A173093 66272686526956073137307690185435702644419625
%N A173093 a(1)=1, a(2)=3, a(n)=a(n-2)*a(n-1)-a(n-2).
%t A173093 a=1;b=3;lst={a,b};Do[c=a*b-a;AppendTo[lst,c];a=b;b=c,{n,14}];lst
%t A173093 RecurrenceTable[{a[1]==1,a[2]==3,a[n]==a[n-2]a[n-1]-a[n-2]},a,{n,20}] (* _Harvey P. Dale_, Feb 09 2014 *)
%K A173093 nonn
%O A173093 1,2
%A A173093 _Vladimir Joseph Stephan Orlovsky_, Feb 09 2010